Tryptophan is an essential amino acid that helps your body produce melatonin and serotonin. However, it's not why you feel tired after a large meal.

The amino acids 5-hydroxytryptophan (5-HTP) and l-tryptophan are precursors of serotonin. 5-HTP is generally recommended over l-tryptophan because it crosses the blood-brain barrier at a higher rate, ...

The development of chemical reactions that can distinguish between the 20 common amino acids with high specificity offers the potential to decipher the sequence, structure and function of proteins.